Two temporal components within the human pulmonary vascular response to ∼2 h of isocapnic hypoxia
Two temporal components within the human pulmonary vascular response to ∼2 h of isocapnic hypoxia
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DOI：
10.1152/japplphysiol.00903.2004
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发表时间：
2005-03-01
影响因子：
3.3
通讯作者：
Robbins, PA
中科院分区：
文献类型：
--
作者：
Talbot, NP;Balanos, GM;Robbins, PA
人类肺血管对缺氧反应的时间进程尚未完全确定。在这项研究中，研究A旨在评估缺氧开始时肺血管张力增加的形式，并确定在随后的20分钟内是否会出现稳定的平台期。12名志愿者暴露于等二氧化碳的正常氧下两次，每次5分钟（潮气末PO 2 = 100 Torr），25分钟等二氧化碳缺氧（潮气末PO 2 = 50 Torr），最后5分钟等二氧化碳正常氧。研究B旨在寻找较慢肺血管反应的开始，如果可能，确定该过程的潜伏期。7名志愿者暴露于5分钟的等二氧化碳正常氧，105分钟的等二氧化碳缺氧，最后10分钟的等二氧化碳正常氧。对于这两项研究，进行了由等二氧化碳正常氧组成的对照方案。多普勒超声心动图用于测量心输出量和收缩期最大三尖瓣压力梯度，并计算肺血管阻力。对于研究A，初始响应可以通过时间常数为2.4 +/- 0.7 min（平均值+/- SE）的单指数过程很好地描述。在此之后，有一个平台期持续至少20分钟。在研究B中，第二个较慢的阶段被确定，与血管张力开始上升后，43 +/- 5分钟的潜伏期。这些结果表明存在两个不同的阶段缺氧性肺血管收缩，这可能是由两个不同的基础过程。
The time course of the pulmonary vascular response to hypoxia in humans has not been fully defined. In this investigation, study A was designed to assess the form of the increase in pulmonary vascular tone at the onset of hypoxia and to determine whether a steady plateau ensues over the following similar to20 min. Twelve volunteers were exposed twice to 5 min of isocapnic euoxia (end-tidal PO2 = 100 Torr), 25 min of isocapnic hypoxia (end-tidal PO2 = 50 Torr), and finally 5 min of isocapnic euoxia. Study B was designed to look for the onset of a slower pulmonary vascular response, and, if possible, to determine a latency for this process. Seven volunteers were exposed to 5 min of isocapnic euoxia, 105 min of isocapnic hypoxia, and finally 10 min of isocapnic euoxia. For both studies, control protocols consisting of isocapnic euoxia were undertaken. Doppler echocardiography was used to measure cardiac output and the maximum tricuspid pressure gradient during systole, and estimates of pulmonary vascular resistance were calculated. For study A, the initial response was well described by a monoexponential process with a time constant of 2.4 +/- 0.7 min ( mean +/- SE). After this, there was a plateau phase lasting at least 20 min. In study B, a second slower phase was identified, with vascular tone beginning to rise again after a latency of 43 +/- 5 min. These findings demonstrate the presence of two distinct phases of hypoxic pulmonary vasoconstriction, which may result from two distinct underlying processes.